Android编程中14个解决实际问题的代码片段

1、查看是否有存储卡插入 

String status=Environment.getExternalStorageState();    
   
if ( status.equals ( Enviroment.MEDIA_MOUNTED ) )    
{    
    说明有SD卡插入    
}  

2、让某个Activity透明

OnCreate中不设Layout     

this.setTheme(R.style.Theme_Transparent);   

以下是Theme_Transparent的定义（注意transparent_bg是一副透明的图片）   

3、在屏幕元素中设置句柄

使用Activity.findViewById来取得屏幕上的元素的句柄，使用该句柄您可以设置或获取任何该对象外露的值。

TextView msgTextView = (TextView)findViewById(R.id.msg);       
msgTextView.setText(R.string.push_me);  

4、发送短信

    String body=”this is mms demo”;     
        
    Intent mmsintent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”smsto”, number, null));     
        
    mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body);     
    mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, true);     
    mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, true);     
        
    startActivity(mmsintent); 

5、发送彩信

    StringBuilder sb = new StringBuilder();     
        
    sb.append(”file://”);     
        
    sb.append(fd.getAbsoluteFile());     
        
    Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”mmsto”, number, null));     
        
    // Below extra datas are all optional.     
    intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_SUBJECT, subject);     
    intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body);     
    intent.putExtra(Messaging.KEY_ACTION_SENDTO_CONTENT_URI, sb.toString());     
    intent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, composeMode);     
    intent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, exitOnSent);     
        
    startActivity(intent);  

6、显示toast

view plaincopy 
Toast.makeText(this._getApplicationContext(), R.string._item, Toast.LENGTH_SHORT).show();   

7、发送Mail

mime = “img/jpg”;    
               
shareIntent.setDataAndType(Uri.fromFile(fd), mime);    
   
shareIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(fd));    
   
shareIntent.putExtra(Intent.EXTRA_SUBJECT, subject);    
   
shareIntent.putExtra(Intent.EXTRA_TEXT, body);  

8、注册一个BroadcastReceiver

registerReceiver(mMasterResetReciever, new IntentFilter(”OMS.action.MASTERRESET”));    
   
private BroadcastReceiver mMasterResetReciever = new BroadcastReceiver()   
{    
        public void onReceive(Context context, Intent intent)   
       {    
            String action = intent.getAction();    
   
            if (”oms.action.MASTERRESET”.equals(action) )   
           {    
                RecoverDefaultConfig();    
            }    
        }    
};

9、定义ContentObserver，监听某个数据表 

private ContentObserver mDownloadsObserver = new DownloadsChangeObserver(Downloads.CONTENT_URI);    
   
private class DownloadsChangeObserver extends ContentObserver    
{    
        public DownloadsChangeObserver(Uri uri)    
        {    
            super(new Handler());    
        }    
   
        @Override    
        public void onChange(boolean selfChange) {}   
     
}    

10、获得手机UA 

public String getUserAgent()    
{    
    String user_agent = ProductProperties.get(ProductProperties.USER_AGENT_KEY, null);    
       
    return user_agent;    
}    

11、清空手机上cookie  

CookieSyncManager.createInstance (getApplicationContext() );    
   
CookieManager.getInstance().removeAllCookie();      

12、建立GPRS连接 

//Dial the GPRS link.    
private boolean openDataConnection()    
{    
    // Set up data connection.    
    DataConnection conn = DataConnection.getInstance();        
       
    if ( connectMode == 0 )    
    {    
         ret = conn.openConnection ( mContext, “cmwap”, "cmwap”, "cmwap” );    
    }    
    else    
    {    
                ret = conn.openConnection(mContext, “cmnet”, "", "");    
     }    
}   

13、PreferenceActivity 用法

public class Setting extends PreferenceActivity    
{    
    public void onCreate ( Bundle savedInstanceState )    
        {    
            super.onCreate ( savedInstanceState );    
            addPreferencesFromResource ( R.xml.settings );     
    }    
}    
Setting.xml:  
[java]   
Android:key=”seting2″   
   
         android:title=”@string/seting2″    
         android:summary=”@string/seting2″/>    
         android:key=”seting1″    
         android:title=”@string/seting1″    
         android:summaryOff=”@string/seting1summaryOff”    
           android:summaryOn=”@stringseting1summaryOff”/>

14、通过HttpClient从指定server获取数据   

DefaultHttpClient httpClient = new DefaultHttpClient();


          HttpGet method = new HttpGet(“/templets/default/index.html”);    
          HttpResponse resp;    
          Reader reader = null;
 
          try {    
              // AllClientPNames.TIMEOUT    
              HttpParams params = new BasicHttpParams();    
              params.setIntParameter(AllClientPNames.CONNECTION_TIMEOUT, 10000);    
              httpClient.setParams(params);    
              resp = httpClient.execute(method);    
              int status = resp.getStatusLine().getStatusCode();    
              if (status != HttpStatus.SC_OK)    
              {   
                 return false;    
              }   
   
              // HttpStatus.SC_OK;    
              return true;
          }    
        catch (ClientProtocolException e)    
        {    
              // TODO Auto-generated catch block    
              e.printStackTrace();    
        }    
       catch (IOException e)    
       {    
              // TODO Auto-generated catch block    
              e.printStackTrace();    
        }   
       finally   
      {    
              if (reader != null)    
              try   
             {    
                  reader.close();    
             }   
             catch (IOException e)    
             {    
                  // TODO Auto-generated catch block    
                  e.printStackTrace();    
             }    
      }   

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